This type of display device has already been put to practical use, and is described as a well-known technique in Patent Document 1, for example.
Patent Document 1 describes a device enabling switching between a state to display an image with high quality and a mirror state to obtain an eye-friendly reflected image suitable for a person to see a face and/or figure of the person to observe. The device is comprised of: an image display part that outputs image light; reflective type polarized light selecting means for transmitting therethrough a first linearly polarized light component outputted from the image display part and reflecting a second linearly polarized light component of which a polarizing axis is perpendicular to that of the first linearly polarized light component; a transmissive polarizing axis variable part capable of selecting whether or not to change a polarizing axis of incident linearly polarized light; and a polarized light selecting member which absorbs, among the incident light, the first linearly polarized light component, and transmitting therethrough the second linearly polarized light component with the polarizing axis perpendicular to that of the first linearly polarized light component, which are arranged in this order. The image display part is provided with absorbent type polarized light selecting means to output the first linearly polarized light as the image light.
Patent Document 1 provides such a configuration, and thus leads to mirror function architecture that adequately endures practical use.
[Patent Document 1] International Application Publication WO 02/069031A1 (particularly, see pages 6 to 7 and FIGS. 1 and 2)